Vaccination significantly reduces morbidity and mortality caused by annual influenza epidemics. Traditionally, influenza vaccines have been manufactured using adapted influenza virus grown in eggs. However, this method suffers from inherent disadvantages such as slow production and allergenic egg proteins in the final product. To avoid these drawbacks, new vaccines made of recombinant hemagglutinin produced in the baculovirus/insect cell system (BICS) have been developed. Although effective, the BICS product has reduced immunogenicity compared to the egg-product, resulting in 3-fold higher vaccine doses and cost. The most distinct difference between egg-produced and BICS-produced hemagglutinin (HA) is the structure of their carbohydrate side-chains, or glycans. The egg product has complex, branched glycans containing galactose, whereas the BICS product has truncated, insect-type glycans without galactose. Recent vaccination studies clearly demonstrate that HA with egg-type glycans induces a much stronger protective immune response than HA with insect-type glycans. Hence, modifying glycan processing in the BICS to yield proteins with egg-type glycans could enhance the vaccine efficacy of BICS-produced HA to match or exceed that of the egg product. GlycoBac proposes to leverage our glycoengineering technology to develop a new baculovirus vector specifically designed to produce HA with egg-type glycans in the BICS. We will accomplish this objective through a goal-oriented research strategy: First, we will create a bacterial strain harboring a new baculoviral bacmid and helper plasmid (Aim 1). Next, we will generate a new modular transfer vector (Aim 2) and use it to transfer a suite of glycosyltransferases genes into the bacmid (Aim 3). Finally, we will use this bacmid to produce pandemic influenza HA with egg-type glycans, and confirm its glycosylation pattern (Aim 4). Together, these aims will yield a baculovirus vector with the demonstrated ability to produce HA with egg-type glycans. GlycoBac focuses on modifying glycosylation in the BICS, and we have extensive experience in the experimental techniques proposed in this Phase I project. Successful completion of our Specific Aims will set the stage for an SBIR Phase II project, which will be designed to test the vaccine efficacy of BICS-produced HA with egg-type glycans in an animal model. In Phase III, GlycoBac will commercialize the glycoengineered baculoviral vectors by licensing them to influenza vaccine manufacturers. Ultimately, the new tools developed in this Phase I project will benefit healthcare consumers through more efficacious vaccines against seasonal and pandemic influenza.